Isolines:

An isoline is a line connecting points of equal value.

Examples of isolines:

Isotherms:

points of equal temperature

Isobar:

points of equal barometric (air) pressure

Contour:

points of equal altitude Concentration of chemicals Anything else you can get a value for.

(The weather channel loves isolines!)

Rules for Drawing Isobars: 1. ALL points on an isobar have the EXACT same pressure

 5  5  10  10  10  10  15  15

2. intervals. Each isobar will have a side where values are higher and a

 5

Isobars are drawn at side where values are

 10

lower.

 10  10  10  15  15

3. Isobars NEVER cross or fork (split): a. Either form closed circles/loops b. Run off the edge of the map c. You may stop at a front line

4. Isobars are ALWAYS labeled.

40 ° 30 ° 20° 50 ° 60 °  X  Y  Z

Gradient Gradient shows how quickly the value changes from one point to another.

Gradient

 

value dis

tan

c e

A steep (high) gradient changes quickly and the isolines are close together.

A gentle (low) gradient changes slowly and the lines are far apart.

Steep area Gentle area

Highlight data points.

Fill in gaps in data.

Connect the dots.

Go on to the next value.

Making a Contour Map II

Drawing Contour Maps III